Rotary wave guide joints



J*1m- 24, 1961 c. l. BRENNALT 2,969,513

ROTARY WAVE GUIDE JoINTs v Filed Jan. 9. 1958 INVENTOR BY 2 ATTORNEY ROTARY WAVE GUIDE JOINTS Chester I. Brennalt, Eau Gallie Beach, Fla., assigner to Western Electric Company, Incorporated, New York, N.Y., a corporation of New York Filed Jan. 9, 1958, Ser. No. 707,918

Claims. (Cl. 333-98) The present invention relates to rotary wave guide joints and more particularly to a rotary wave guide joint for coupling two' sections of axially aligned rectangular wave guides capable of angular displacement relative to each other.

Rotary joints of the nature of this invention are capable of use in the connection of rectangular wave guide sections used in airborne radar systems, or the like, in which the transmitter is stationary and the antenna is rotatable, Rotary joints generally have been` circular in cross section for mechanical reasons and, consequent- 1y, coaxial cables, have been used to join the rectangular sections of wave guide. The central conductor of-the coaxial cable served not only as a conductor, but also as a probe at each end for taking the energy from one rectangular wave guide section and for delivering the conducted energy to another rectangular wave guide section.

Clearly, a ield pattern of electromagnetic energy is changed materially when taken from a rectangular guide and conducted through a circular guide for delivery to a second rectangular guide. Modes of operation having axial symmetry, such as the TMnl mode, are the ones best suited for transmission through the coaxial rotary joint,l other modes being aifected adversely. Moreover, the circular joint does not admit of rotation of the field pattern as is sometimes desired for purposes of impedance matching and polarization for radiation. This invention overcomes these limitations and does so with a minimum of loss occasioned by leakage of the energy While passing through the joint.

An object of this invention is improved rotary wave guide joints.

Another object of the present invention is the provision of a rotary wave guide joint which maybe used to place a twist in axially and angularly aligned Wave guide sections. j Y

Another object is to provide a rotary wave guide joint capable of insertion between two sections of wave guide which are axially aligned but angularly displaced rwith respect to each other.

A further object of the invention is the provision of a rotary wave guide joint which may be used to connect an oscillatively rotatable section of wave guide to a iixcd section of wave guide.

Still another object of this invention is the .provision of a rotary wave guide joint which is capable of electrically joining two sections of rectangular wave guide with minimum leakage of radio frequency energy transmitted therethrough.

Apparatus illustrating certain features of the. Present invention for coupling two sections of tubular wave guide which are axially aligned and angularly displaceable about a common axis may include a plurality of members supported in stacked relation and rotatable independently` about a common axis, said members being provided with apertures communicating with one anto provide new and Patented Jan. 24,1961

other, and means for turning the members about their common axis.

A complete understanding of the invention may be had by reference to the following detailed description of a device forming a specific embodiment thereof, when considered in connection with the accompanying drawings, in which like reference numerals designate like parts throughout the gures thereof and wherein:

Fig. l is a vertical sectional view of the device taken along the longitudinal axis thereof;

Fig. 2 is a horizontal section taken along line 2--2 of Fig. 1 viewed in the direction of the arrows;

Fig. 3 is an enlarged, fragmentary view of a spacer and bearing ring assembly forming part of the device shown in Fig. 1; and

Fig. 4 is a perspective view of the spacer ring and bearing ring assembly shown in Fig. 3. `v

There is shown in Fig. l a hollow housing 11 having an elliptical top surface 12, a subjacent bottom surface 13 of elliptic shape, and a continuous side Wall 14 joining the top and bottom surfaces.

Vertically positioned within the housing 11 is a nest of gears 15, 16, 17, and 18, of uniformly varying diameter, arranged in order of progressively increasing diameter from the top to the bottom of the nest. Vertical spacing of the gears 15 to 18, inclusive, relative to one another and attainment of horizontal alignment of the gear nest configuration are accomplished by intel-posing a` spacing ring 19 of stainless steel, or other suitable Wear-resistant material, accompanied by bearing rings 21-21 of similar material disposed on both the top and the bottom surfaces of the spacer ring 19 (Fig. 3), between cach of the stacked gears and between the gear 18 and the housing 11. The rings 19-19 are closely fitted in annular grooves 22-22 provided in the opposed faces of the respective gears 15, 16, 17, and 18 such that rotation of each of the gears is possible without horizontal displacement. The bearing rings 21-.21 are shown associated with spacing rings 19-19 in detail in Fig. 4.

The gear 15 is formed with an upright annular collar 23 which contains tapped openings 24-24 arranged in a manner to receive fastening members 25-25. A rectangular wave guide section 26 is coupled to the collar 23 by means of the fastening members 25-25 inserted through the wave guide iiange 27 into engagement with the tapped openings 24-24.

A securing ring 28, threadedly positioned in a circular opening 29 of the top surface A12 of housing 11, slidably receives the collar 23 through a central aperture 30 formed through the ring 2S, and in this manner the 'ring 2.8 contains the gearsv 15,. 1.6, 17 and .18 in. vertical coaxial alignment with the wave guide section 26. Im.- mediately below the securing ring 2.8 is a planar ring 3l of stainless steel, for example, which is positioned on the. upper surface 32 of the gearA 15 to.. provide a wearing surface between the gear surface 32 and the securing ring 28. An annularslot 33 is provided in the gear surface 52 into which is placed an Q ring34, preferablypof resilient, rubber-.like material which is suitable for sealing the opening 30 to the interior of housing 11.

Centrally formed in each of the gears 15, 16, .17, and 18 is a rectangular aperture 35 of a size corresponding to the inner cross-sectional contour of wave guide section 26 and, when the gears 15 to 18, inclusive, are assembled in nested relationship, the apertures 35,-=35 are coaxially aligned. A second wave guide section36 is shown attached at a flange connection 37 to a rectangular tubing 3S integrally formed, for example, with the bottom surface 13 of housing.I 11. The bottom surface 13 is in turn provided with a rectangular opening 39 which is coaxial with the aperture 35 of each gear which corresponds in size to the inner cross-sectional contours of the rectangular wave guide sections 26 and 36 and tubing 38. A continuous channel for conveying and guiding wave energy is thus completed from the fixed wave guide section 36 to the wave guide section 26.

Inasmuch as the rectangular channel established by the wave guide sections 36 and 26, the rectangular path defined by the gear rectangular apertures .3S- 35, and the tubing 38 is to be considered preferably as having a uniform parameter in order to maintain throughout the channel a distributed impedance at the operating frequency of electromagnetic energy, it becomes desirable to connect electrically the loosely stacked gears 15, 16, 17, and 18. This connection is accomplished by the provision of well-known radio frequencyy choker. to prevent leakage of energy or interruption of the standing wave ratio.

Such a choke is furnished by means of an `annular cavity 41 provided in the lower face of each of the gears 15, 16, 17, and 18 at a distance of approximately a quarter-wave length from the mid-point of the long side of the rectangular aperture 35 to the inner diameter of the cavity 41, the axial depth of cavity 41 being of such an amount that the total distance from the aperture 35 to the bottom of the cavity d1 is the equivalent of substantially one-half wave length. Thus when energy attempts to leak through the interstices between adjoining gears, standing waves are set up in the aforementioned approximate one-half wave length distance. The short circuit at the bottom of the cavity reflects through the axial depth of the cavity 41 as a high impedance which is transformed to a low impedance across the approximate quarter-wave section from the inner diameter of the annular cavity 41 to the edge of the aperture 35. The choke provided thus short-circuits the sides of an aperture 35 of one gear with the sides of the aperture 35 of the adjacent gear, and thereby electrically joins one aperture 35 with another.

A means to rotate the loosely stacked nest of gears 15, 16, 17, and 18 is an idler gear 4?., preferably integrally formed as shown in Fig. 1. The idler gear 42 is provided with a series of stepped gear faces iii-d3, thereby uniformly varying the diameter of gear 42 in order of progressively decreasing diameter from the top to the bottom of the gear 4t2. The gear 42 is disposed vertically in the housing 11 by bearings 44--44 which rotatably are received in journals 45-45 so as to mesh the gear faces 43-43 with the loosely stacked nest of gears to 18, inclusive.

Operation The wave guide section 26 is engaged cooperatively to an antenna drive mechanism, designated generally as 46, which mechanism, for example, may impart positive oscillatory rotation to the wave guide section 26. It can be observed readily that the rotational movement of the guide section 26 is transmitted directly to the gear 15 by the rigid connection afforded between the section 26 and the collar 23 of the gear 15.

The gear 15 drives the idler gear 42 through a smaller angle of rotation than that of the gear 15 inasmuch as the gear 15 is of smaller diameter than the diameter of the gear face 43 with which it meshes. This positive drive imparted to the gear 42 rotates each of the gears 16, 17, and 18 through -a progressively different angle of rotation which increases from the gear 18 upwardly toward the gear 15 due to the loose stacking of the gears 15 through 18. Since each of the gears 15, 16, 17, and 18 will slip relative to one another, and since each have formed therethrough a wave guide aperture 35, the fixed tubing 38 which is suitably connected to an RF transmitter 40 by the wave guide section 36 will see at the opening 39 an axially twisted guide formed by the apertures 35 and the Wave guide section 26. The d'egree of axial twist possible in the rotary joint shown in Fig. l may be dened by the gearing ratio chosen between the idler gear 42 and the nest of gears 15, 16, 17, and 18. Of course, the smoothness of the twist imparted between wave guide sections coupled by this invention is proportional to the number of rectangularly apertured gears chosen to be incorporated in the joint. For purposes of illustration, each of the apertures of the gears 15 to 18, inclusive, of Fig. l, may be approximately one-quarter Wave length in axial thickness such that a smooth transition of the conducted energy from one gear to the other is made possible.

The present invention of a rotary wave guide joint is advantageous when it becomes necessary to provide a rotatable wave guide connection between sections of a wave guide which are axially aligned but angularly displaced about a common axis. The device has good power handling and standing wave characteristics such that wave guide sections having distributed parameters may be coupled and twisted relative to each other without disturbance of the transmission qualities of the overall waveguide.

Obviously many modiiications and variations of the present invention are possible in the light of the above teachings. 1t is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. In a wave guide, a rotary joint for coupling two sections of said Wave guide which are axially aligned and angularly displaceable about a common axis comprising a housing having a top and a bottom, a nest of rotatable gears coaxially aligned and vertically disposed within said housing, each of said rotatable gears having a different diameter and each being arranged in order of progressively increasing diameter from the top to the bottom of said nest, each of said gears having an annular recess in the opposite faces thereof, the inner surface of the bottom of the housing having an annular recess in vertical alignment with the recess of the adjacent face of the lowermost gear, a member positioned within adjacent recesses to maintain vertical spacing and horizontal placement of each gear with respect to another, each of said gears being independently rotatable with respect to another and eachhaving centrally formed therethrough an aperture corresponding in size and shape to the innerwall configuration of said wave guide, drive means situated within said housing to rotate simultaneously each of said gears through a progressively diierent angle of rotation, and means connecting each of said sections of wave guide to said housing so as to form a continuous wave guide channel from one section of said wave guide through the apertures of said rotatable gears to the other section of said wave guide.

2. In a wave guide, a rotary joint for coupling two sections of said wave guide which are axially aligned and angularly displaceable about a common axis comprising a housing having a top and a bottom, a nest of independently rotatable gears coaxially aligned and vertically disposed within said housing, each of said gears having a different diameter and arranged in order of progressively increasing diameter from the top to the bottom of said nest, each of said gears having an annular recess in the opposite faces thereof, the inner surface of the bottom of the housing having an annular recess in vertical alignment with the recesses of the adjacent face of the lowermost gear, a plurality of ring members positioned within adjacent recesses to provide a uniform vertical spacing between adjacent gears and to maintain said gears in horizontal alignment, each of said independently rotatable gears having formed centrally therethrough an aperture corresponding in size and shape to the inner-wall configuration of said wave guide, radio frequency choke means arranged between each of said gears to short circuit energy attempting to leak through the interstices between adjacent gears, drive means situated within said housing to rotate simultaneously each of said gears through a progressively diiferent angle of rotation, and means connecting each of said sections of Wave guide to said housing so as to form a continuous wave guide channel from one section of said wave guide through the apertures of said gears to the other section of wave guide.l

3. In a wave guide, a rotary joint for coupling two sections of said wave guide which are axially aligned and angularly displaceable about a common axis comprising a housing with a bottom provided with an opening corresponding in size and shape to the inner-wall configuration of said wave guide and a top provided with an opening therethrough, a nest of independently rotatable spur gears coaxially aligned and vertically disposed within said housing, each of said gears having a different diameter and arranged in order of progressively increasing diameter from Vthe top of the bottom of said nest, each of said gears having an annular recess in the opposite faces thereof, the inner surface of the bottom having an annular recess in vertical alignmenty with the recess of the adjacent face of the lowermost gear, a ring member interposed within adjacent recesses to provide a uniform vertical spacing between the gears and to maintain said gears in horizontal alignment, each of said independently rotatable gears having formed centrally therethrough an aperture in axial alignment with the opening in the bottom of said housing corresponding in size and shape to the inner-wall configuration of said Wave guide, the lower face of each gear having an annular cavity formed therein of approximately one-quarter wave length in axial depth and at a distance from the centrally disposed gear aperture of approximately one-quarter wave length of the energy to be conducted through said wave guide so as to serve as a radio frequency choke thereby electrically connecting the independently rotatable gears, an idler gear of varying diameter decreasing from the top to the bottom designed to mesh with the independently rotatable gears of said nest so as to impart to each gear progressively increasing angular rotation from the bottom of said nest of gears to the top, means for rigidly connecting one section of said wave guide to the bottom of said housing in axial communication with the opening therein and With the apertures of said gears, the uppermost gear of said nest of gears having a collar extending through the opening in the top of said housing and designed to rotate therein, the uppermost section of said idler gear being arranged to mesh with the uppermost gear of said nest of gears, fastening means to engage cooperatively the other section of wave guide to the collar to the uppermost spur gear such that rotation of said other section of Wave guide positively drives the uppermost gear of the nest of gears and the idler gear in order to impart rotation to said independently rotate able spur gears.

4. In a Wave guide, a rotary joint for coupling two sections of said wave guide which are axially aligned and angularly displaceable about a common axis comprising a housing having a bottom provided with an opening corresponding in size and shape to the inner-wall conguration of said wave guide and a top provided with a circular opening therethrough, a ring closure detachably receivable into said top opening for reducing the diameter of said opening, a nest of independently rotatable spur gears coaxially aligned and vertically disposed within said housing and vertically adjustable by axial movement of said ring closure, each of said gears having a different diameter and arranged in order of progressively increasing diameter from the top to the bottom of said nest, each of said gears having an annular recess in the opposite faces thereof, the inner surface of the bottom of the housing having an annular recess in vertical alignment with the recess of the adjacent face of the lewemwst geef formed therein, a ring member pesi-f tioned within adjacent recesses so as to provide a uniform vertical spacing between the gearsgand to maintain said gears in horizontal alignment, each of said independently rotatable gears having formed centrally therethroughan aperture in axial alignment with the opening in the bottom of said housing corresponding in size and shape to the inner-wall configuration of said Wave guide, the lower face of each gear having an annular cavity formed therein of approximately one-quarter wave length in axial dept hand at a distance from the centrally disposed gear aperture of approximately one-quarter wave length of the energy to be conducted through said wave guide so as to servel as a choke thereby electrically connecting the independently rotatable gears, the uppermost gear of said nest of gears having an annular collar adapted slidably to extend through the opening of said ring closure, mois,- ture seal means positioned between said closure and said uppermost geen an idler gear of verving diameter decreasing frorn the top to the bottom rotatably held within said housing in horizontally adjacent relationship with respect to said nest of gears and adapted to mesh with the independently rotatable gears of said nest so as to impart to each gear progressively increasing angles of rotation Ifrom the bottom of said nest of gears to the top, said idler gear being driven by the uppermost gear of the nest of gears, means rigidly connecting one section of said Wave guide to the bottom of said housing in axial communication with the opening therein and with the apertures of said gears, means operatively connecting the other section of wave guide to the collar of the uppermost gear of the nest of gears in axial alignment with the apertures of said gears such that rotation of said other section of wave guide positively drives the uppermost gear of said nest of gears and said idler gear in order to impart rotation to said independently rotatable spur gears.

5. A wave guide rotary joint for coupling two sections of a wave guide, which comprises independently rotatable members supported in axially aligned stacked relationship and provided with apertures communicating with one another and the sections of the wave guide to be coupled, each of said members having an annular recess in the opposite faces thereof, means situated within adjacent recesses to uniformly and axially space apart the rotatable members, and means engaged with the rotatable members for revolving simultaneously said members about their common axis.

6. A wave guide rotary joint for coupling two sections of a wave guide, which comprises independently rotatable members supported in axially aligned stacked relationship and provided with apertures communicating with one another and the sections of the wave guide to be coupled, each of said members having an annular recess in the opposite faces thereof, means situated within adjacent recesses to uniformly and axially space apart the rotatable members, radio frequency choke means arranged between each of said members to short-circuit energy attempting to leak through the interstices between adjacent members, and means engaged with the rotatable members for revolving simultaneously said members about their common axis.

7. A wave guide rotary joint for coupling two sections of a wave guide, which comprises a housing having a top and a bottom, each with an aperture in vertical alignment with the other, said apertures communicating with the sections of the wave guide to be coupled, independently rotatable members supported in axially aligned stacked relationship and provided with apertures communicating with one another and with the apertures of the top and bottom of the housing, each of said rotatable members having an annular recess in the opposite faces thereof, the inner surface of the bottom of the housing having an annular recess in vertical alignment with the recess of the adjacent face of the lowermost rotatable member, a spacing ring situated within adjacent recesses, and means engaged with the rotatable members for revolving simultaneously said members about their common axis.

8. A wave guide rotary joint for coupling two sections of a wave guide, which comprises a housing having a top and a bottom, each with an aperture in vertical alignment with the other, said apertures communicating with the sections of the wave guide to be coupled, independently rotatable members supported in axially aligned stacked relationship and provided with apertures communicating with one another and with the apertures of the top and bottom of the housing, each of said rotatable members having an annular recess in the opposite faces thereof, the inner surface of the bottom of the housing having an annular recess in vertical alignment with the recess of the adjacent face of the lowermost rotatable member, a spacing ring having an upper and lower surface and situated within adjacent recesses, a bearing ring positioned adjacent both the upper and lower surfaces of the spacing ring, and means engaged with the rotatable members for revolving simultaneously said members about their common axis.

9. A wave guide rotary joint for coupling two sections of a wave guide, which comprises a housing having a top and a bottom, each with an aperture in vertical alignment with the other, said apertures communicating with the sections of the wave guide to be coupled, independently rotatable members supported in axially aligned stacked relationship and provided with apertures communicating with one another and with the apertures of the top and bottom of the housing, each of said rotatable members having an annular recess in the opposite faces thereof, the inner surface of the bottom of the housing having an annular recess in vertical alignment with the recess of the adjacent face of the lowermost rotatable member, a spacing ring situated within adjacent recesses,

8 moisture seal means slidably positioned within the annular recess of the upper face of the uppermost rotatable member and slidably engageable with the inner surface of the top of the housing, and means engaged with the rotatable members for revolving simultaneously said members about their common axis.

10. A wave guide rotary joint for coupling two seetions of a wave guide, which comprises a first nest of independently rotatable gears supported in axially aligned stacked relationship in order of progressively increasing diameter from top to bottom and provided with apertures communicating with one another and the sections of the wave guide to be coupled, each of said gears having an annular recess in the opposite faces thereof, means situated within adjacent recesses to uniformly and axially space apart the rotatable gears and hold said gears from lateral displacement, and a second nest of dependently rotatable gears supported in axially aligned stacked relationship in order of progressively decreasing diameter from top to bottom such that the rst and second nests of gears are mutually engaged.

References Cited in the file of this patent UNITED STATES PATENTS 1,759,335 Wolkoif May 20, 1930 2,100,936 Bonn Nov. 30, 1937 2,438,119 Fox Mar. 23, 1948 2,451,876 Salisbury Oct. 19, 1948 2,529,381 Frear Nov. 7, 1950 2,668,191 Cohn Feb. 2, 1954 OTHER REFERENCES Ragan: Microwave Transmission Circuits, published by McGraw-Hill Book Co., Inc., N.Y., in 1948, pages 432- 437. 

